CI and PR template improvements

Proposed changes

This change improves the DevOps portion of this repo in the following ways:

Adds a standardized Pull Request template
Adds a CI check to ensure that the Helm chart appVersion is not updated without also bumping the chart Version
Adds a CI check to ensure that the chart changelog is updated if the chart is updated
Improves reliability of the publish GH action
- The chart-releaser-action will attempt to run if git detects any changes at all in the chart directory.
- This means if a change was merged, but we aren't yet cutting a release by bumping the version number, git will still detect changes and so chart-releaser-action will attempt to run.
- It will create a tarball and attempt to create a release, but under the same version as the current/latest version. GitHub will return an error complaining that a release already exists under that name/version:
```
Error: error creating GitHub release deepgram-self-hosted-0.2.2-beta: POST https://api.github.com/repos/deepgram/self-hosted-resources/releases: 422 Validation Failed [{Resource:Release Field:tag_name Code:already_exists Message:}]
```
- So instead, this PR adds an explicit check to see if the Chart version has been bumped before taking the GH action

What types of changes does your code introduce to the Deepgram self-hosted resources?

[ ] Bugfix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[x] Documentation update or tests (if none of the other choices apply)

[x] I have read the CONTRIBUTING doc
[x] I have tested my changes in my local self-hosted environment
- I tested all GH action modifications locally using act.
[x] I have added necessary documentation (if appropriate)